Mining  machine



Oct. 9 1-923.

5 Sheets-Sheet 1 M. P. HOLMES MINING MACHINE Filed July 16 1919 Oct. 9 1923,

P. HOLMES MINING MACHINE Filed July 16 1919 5 Sheets-Sheet 2 Oct. 9, 1923. 1,470,573

M. P. HOLMES MINING MACHINE Filed July 16 19 19 5 Sheets-Sheet 5 1141 Q 119a? v 69 L 34 51 x 4 [1 830/ Z- [I i 8i i 84 25 l -55 illi/[1111111017 Oct. 9

5 Sheets-Sheet 4 Filed July 16 1919 BMW 8w kw mum QNN hwNN xxx Oct. 9 1923.

. 1,470,573 M. P. HOLMES MINING MACHINE Filed. July 16 1919 5 Sheets-Sheet 5 516. 51/7 w A NW" x'-f iiii --v ATM. v"

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I F .41. M 501 pg 4Z1 17 0 .11; I m w Patented Oct. 9, 1923.

UNITED stares 1,470,573 PATENT OFFHJE.

IMORRIS P. .HOLIICES, OF CLAREMONT, NEW HAMPSHIRE, ASSIGNOR TO SULLIVAN MACHINERY COMPANY, A COB-PORA'I'IUN OF .lyIASSACHUSETTS.

MINING :trnonrnn.

Application filed July 16, 1919.

tain new and useful Improvements in Min ing Machines, of which the following is a full, clear, and exact specification.

This invention relates to mining machines and more especially to that type of mining machine used for cutting kerfs in the new terial to be mined.

In mining machines heretofore used the feeding or driving means and the controlling means therefor have been rather complex and have absorbed energy in mechanical connections which render the operation and control of the mining machine somewhat difficult, and the constructions have been machine for inspection and repair somewhat difficult. Further, the construction and operation of these machines have been such that, when the controlling devices were operated to increase the pull on the cable or chain which advances the machine along the face of the material to be mined, increased wear resulted in bearings which were very diiiicult to get at, causing these hearings to wear rapidly.

In mining machines of the character referred to it is customary to provide, in the feeding mechanism, a yielding element, or friction, adapted to yield when excessive resistance is encountered in order to prevent breakage of or other injury to the machine. Means are also usually provided for loading the friction, or varying the resistance to yielding interposed thereby, it being desirable to permit a greater resistance under some conditions of use than under others.

in practice, however, machine runners will nism of mining machines adapted to per-.

1 mit convenient and accurate regulation of the friction. and prevent accidental or insuch as to render accessibility of the mining Serial No. 311,321.

tentional overloading thereof under improper conditions, said controlling means be ing of such a character that the parts thereof may be easily removed for inspection or repair. These and other objects and advantages will however hereinafter more fully appear.

In the accompanying drawings are shown for illustrative purposes several embodiments which the invention may assume in practice. I

In said drawings:

Fig. l is a plan view of a part of a mining machine embodying one form of the invention.

Fig. 2 is a longitudinal vertical sectional view substantially on the line 2-2 of Fig. 1.

Fig. 3 is a sectional plan view of a part of the machine cover and controlling means.

Fig. 4 is a detail rear elevation of a part of i the controlling means.

Fig. 5 is a transverse vertical sectional view taken substantially on the line 55 of Fig. l.

Fig. 6 is another vertical sectional view taken substantially on the line 6-6 of Fig. 3.

Fig. 7- is a detail vertical sectional view through the friction clutch of the feeding mechanism.

Fig. 8 is a detail horizontal section of a modified form of controlling means.

Fig. 9 is a similar view of still another modified form of controlling means.

Fig. 9 is a detail sectional view on line 9u 9a f :big 9 Fig. 10 is a side elevation of one end of a mining machine provided with the controlling means illustrated in Fig. 9.

Fig. 11 is a longitudinal vertical sectional view through the machine cover showing a further modified form of controlling means.

Figs. 12 and 13 are horizontal sectional views illustrating still further modifications.

F 12 is a detail sectional view on lin 12 12 of Fig. 12.

In F ig. l is shown a mining machine having a frame 1 and provided with actuating means, as an electric motor 2, which is adapted to drive, through a suitable train of driving gears or other means, the feeding member, herein shown as a feed sprocket 3 rotatably mounted on an upright shaft 3 (Fig. 2). The mining machine is also provided, near the rear end thereof, with a'cover plate 4 which supports, in a frame.

manner. to be hereinafter described, a part of the controlling mechanism of the ma chine. The motor 2 may be controlled to rotate in either direction through the operation of a suitable controller and a reverse switch 6, herein shown as mounted on one side of the mining machine.

The motor 2 (Fig. 1) drives a shaft 7 which in turn drives a jack shaft 8 (Fig. 2) through suitable driving means, as a bevel gear 9 carried on one end of the shaft- 7" and abevel gear 10 mounted on the jack shaft 8. This jack shaft turns in suitable bearings 11 and 12 and carries a driving pinion. 13 which drives a relatively large. spur gear 14 whose hub 15 is at tached to an upright shaft 16 herein shown as-v supported in a bearing 17 carried by the bottom plate of the mining machine Rot-atably mounted on the hub 15 is a driving sprocket wheel 18 adapted to drive a cutter chain 19,.the connection between the driving sprocket 18 and the spur gear 14 comprising a clutch mechanism 20 1 controlled through well known connections (not, shown) by a shipper ring 21 and a controlling. handle 22 in such a manner that when. the handle 22 is depressed the gear 14 and the sprocket 18 are disconnected, and when the handle 22 is elevated the gear 14 is positively connected to the sprocket wheel. to drive the cutter chain 19 to cut akerfin. the. coal or other material to be mined.

The feed sprocket 3, which drives the usualcable or chainfor advancing the machine along the mine face, is preferably drivenv from the vertical shaft 16 through gearin including: a. pinion 23: rotatably mounted on a bushing, 24carried1 by a reduced portion.

37- of. saidi shaft. The pinion 23 carries on its upper endran: enlarged hollow casing 25 whichin turn carries and is attached to an annular frictional clutch member 26. Cooperating with this frictional clutch member. 26: is a second annular frictional clutch member or friction band27 which is preferably carried by and rotatable with the shaft 16: through a plurality of radially reciprocable plungers or pistons 28 which are connected to and preferably support the friction band'27 by. radially projecting pins 29, the pistons 28 in turn being sup ported in radial cylinders 30 carried by a hub 31 secured to a reducedportion 32 of theshafta 16,- as-by splines 33. An annular cover. or ring 34:is preferably provided to close. the joint between the normally rotating hub- 31 and. the friction band: 26 to prevent dirt or other foreign particles from working into the: clutchmechanism.

When the motor. 2 is rotating, the shaft 16.- will be rotated thereby, but the pistons 28 are normally in retracted position, so

hereinafter further described. and.

that the clutch members 26 and. 27 will not frictionally engage to drive the pinion 23 with the shaft 16, and this pinion will normally remain stationary, the shaft 7 16 turning within the bushing 24, and the pinion 23 resting on and being supported by a bushing 35 herein shown as supported by a shoulder 36 adjacent the reduced portion 37 of the shaft 16. When it is desired to rotate the pinion 23 to actuate the feed sprocket 3 to move the mining machine, the annular friction band 27 is expanded and forced outwardly into a predetermined frictional engagement with the friction band 26 by the pistons 28, which may be moved radially outward from the shaft 16 by the application of fluid pressure to the rear surfaces 38 of these pistons. F or this purpose, I have preferably used a hydraulic mechanism for applying-thepressure to these pistons, suitable packing means as, cup leathers 39, being provided on the pistons 28 to prevent leakage of the oil or other liquid employed.

In the form of the invention illustrated in Figs. 1 and 3, the oil or other liquid used in the hydraulic controlling means is caused to transmit a; pressure, generated in a cylindrical casing 40 formed in the cover plate 4, through a passage or conduit 41, annular recesses 42, 43 (Fig. 7), and radial ports 44, 45, to a passage 46 formed in the hub 31 and: having branches. leading to the rear heads 38 of the pistons 28.

The annular recess 42 andports 44 are formed inv an. annular channel iron 47 which surroundsthe upper end of the hub 31 and is. preferably held in a cylindrical chamber 48 in the cover plate 4 between packing leathers 49 by a screw cap or. plug 50; By this. improved construction the. cover 4, which carriesv the cylindrical casing 40, passage 41 and. channel. iron.

47, is removably connected to the hub- 31 in such a manner as to provide a bearing for said hub and consequently an upper bearing for the shaft 16. When it is desired to remove. the cover 4, and with it the parts formed therewith or carried thereby, the passage 41' is preferably closed, as by means of a valve 51 which prevents leakage from the hydraulic system.

The pressure may be applied to the oil or other liquid in the passage 41, and therethrough to the pistons 28, in a variety of ways, means being preferably provided for applying a graduated pressure up to either of two predetermined limits, so that when the mining machine isoperated for one purpose one predetermined limiting frictional engagement of the members 26. and 27 may be maintained, and when the mining ma chine is operated for another purpose or in another way another'frictional engagement between the members26 and 27 may be maintained. As shown in Fig. 3, the devices for accomplishing these results are as follows: Located within one end of the cylindrical casing 4:0, and seated against a stop shoulder 52 therein, is a cylinder head having a sleeve portion which extends part way through the bore of the casing while threaded into the opposite end of said casing is a similar cylinder head 541- between which and the head 53 is interposed a spacing member 55; suitable packing means, as cup leathers 56, being provided between the spacing member 55 and the cylinder heads 53 and 5a to prevent leakage of oil therebe tween. The central spacing member 55 is preferably provided with a series of radial openings 57 which communicate with an an nular groove 58 also formed in the member 55 and communicating with the passage 41. The spacing member; 55 and heads 53 and 54; with their oppositely disposed sleeve portions collectively constitute a cylinder lining within which is a pair of oppositely dis posed pistons 59 and 60, said pistons being normally held in spaced relation against shoulders 61 and 62 formed on the heads 53 and 5% respectively by a light spring 64 interposed between said pistons. Each of the pistons 59 and is preferably axially aper tured to receive a piston rod 65 and is also provided with a plurality of cup leathers 66 to prevent leakage of oil through the axial passage about the piston rod, said cup leathers being held in place byplugs 66* seated in threaded recesses formed in the inner faces of the pistons. The pistons 59 and 60 are independently movable upon reciprocation of the piston rod 65, the piston 59 being moved toward the centerot the cylinder by a shoulder 67 formed on the piston rod, and the piston 60 being moved toward the center of the cylinder by suitable nuts 68 threaded onto the end OTE the piston rod, it being ap parent that when one piston is being moved with the piston rod the other piston is held stationary against the cooperating shoulder formed on one of the cylinder heads by; the spring ea. To reciprocate the piston rod 65 to actuate either of the piston heads there is preferably provided a controlling lever 69 suitably pivoted, as to the upper end of the shaft 3 (Fig. 9), by a bolt 70, said lever being retained in either adjusted position by means of catches 71. 72 which are engaged by hooked lugs 71, 72 (Fig. l) on a swiveled handle 69 carried by said lever. This pivoted lever 69 carries on the inner end thereof a shipper yoke 73 which partially encircles the piston rod 65 and is normally in engagement with two collars 7 and 7 5 which are held against the opposite sides of said shipper yoke by springs 7 6 and 77, preferably of different strength, the tension of these springs being regulated by suitable nuts 78 and 79 in threaded engagement with the piston rod and between which and said springs are interposed collars 78 and 79 As will now be seen, pressure applied in either direction to the lever 69 will be transmitted, through the collar Tel or T5, spring 76 or 77, collar 78 or 79, and nut 78 or T9, to the piston rod 65. Consequently, by moving the lever 69 in one direction or the other, one of the pistons 59 or 60 will be moved toward the center of the cylinder, and pres sure will be applied to the liquid in the sys tern, and through said liquid to the rear heads of the pistons 28, to force the annular normally rotating friction element 27 into frictional engagement with the nor mally non-rotating frictional element and thereby drive the pinion 23.

Each of the springs T 6 and '77 is held under an initial compression determined by the adjustment of the nuts 78 and 79, it being possible to place them under dirleren initial compressions by reason oi the abutment of the collars T l, "(5 upon nuts '73 located between the nuts 78, 79, so that when the lever 69 is moved in either direction said springs will act as rigid elements to trans mit the pressure of said lever to the piston rod 65 until said pressure becomes sutficiently great to exceed the initial tension of the springs, after which said springs will yield and prevent any considerable additional pressure from being transmitted from said lever to said piston rod. The spring "I? is preferably heavier than the spring 7 6, so that a greater pressure may be applied to the piston 59 than to the piston 60. Consequently, when the lever 69 is moved in a counter-clockwise direction, the frictional members 26 and 27 will be forced together with a greater pressure than when said lever 69 is moved in a clockwise direction.

The cylinder 50 and the conduit 4:1 con nected therewith are preferably formed integral with the cover a, while the other parts of the pressure generating mechanism are also carried by said cover, so that it is only necessary to take this comparatively small cover to the shop in order to repair any part of the apparatus. Further, the cylinder lining, herein shown as composed of the cylinder heads 53 and 5e and the spacing member 55 therebetween, is preferably formed separately from the cylindrical casing 40 in order that these parts may be easily and correctly machined. The construction also prevents unauthorized readjustment oi the pressure limiting means (that is, the nuts 78 and 79) by the operator. so that he can not apply an excessive pressure when hard work is to be done and then. after he has broken parts of the machine through this excessive pressure, return the parts to the previous position so that an inspector cannot determine why these parts have given way. 'This is common practice among mining machine runners but one which is impracticable with the present construction, because of the labor, difficulty, and time required in removing the heavy cover in order to get access to nuts 78 and 79.

In order to compensate for any slight leakage from the pressure generating apparatus, there is provided, preferably adjacent the cylinder casing 40, and carried by the cover 4, an oil reservoir 80 having a port 81 opening into the passageway 41, this port being preferably noranally closed by a check valve 82 having a light closing spring 82". After the lever 69 has been released and assumes the neutral position illustrated in Fig. 3, oil will auto matically flow trom the reservoir 80through the port 81 into the passageway 41 to ottset any leakage in the system. But when the lever 69 is thrown in either direction to generate pressure in the hydraulic controlling means, oil will be kept from returning to the reservoir 80 by the check valve 82.

The driving pinion 23, whose rotation by the shaft 16 is controlled by the operation of the controlling lever 69, in turn drives t e feed sprocket 3 in either direction throa suitable driving connections. is herein shown the pinion 23 meshes with a gear 83 1 and 5) rotatably mounted on an upright shaft 83 fixed in the machine ca ing and having slidably mounted thereon a reciprocating double ended'clutch sleeve 84 carrying a pinion 85 and movable in opposite directions from the neutral position shown in Fig. 5 to engage the same with either the gear 83 or a gear 93 also rotatably mounted on the shaft 83. The pinion 85 meshes with a spur gear 86 (Fig. 2) mounted. on the hub 87 of the feed sprocket 3. Engagement of the sleeve 84 with the gear 83 causes the pinion 85 to be directly driven by said gear 83, thereby rotating the feed sprocket 3 in one direction. If it is desired to rotate said feed sprocket in the opposite direction, the clutch sleeve 84 may be shifted in the opposite direction into engage ment with the gear 93, the gear 83 then driving the pinion 85 through a train of gearing comprising a pinion 88 formed on the hub of the gear 83 and a pair of connected coaxial gears 89, one of which meshes with the pinion 88 and the other of which meshes with a gear 91 (Fig. 6) secured to a sleeve rotatably mounted on an upright shaft 90 and carrying a gear92 which meshes with the gear 93. It will be seen that by moving the clutch sleeve 84 into one extreme position the feed sprocket 3 Will be driven relatively slowly in one direction, and that when said clutch sleeve is shifted to the limit of its movement in the opposite direction said feed sprocket will be rotated more rapidly in the opposite direction. When the sleeve 84 is in the neutral position illustrated in Fig. 5

the feedsprocket is not driven, and the mining machine is not moved thereby.

The clutch sleeve 84 is shifted by means of a shipper lever 97 (Fig. 1) which is operated by an eccentric pin on a shaft 96 connected by bevel gears with a pivoted o ierating handle 94. The handle 94 is shown in full lines in Fig. 1 in the neutral position from which it may be moved into the dotted line position A to produce the fast feed or into the dotted line position B to produce the slow feed. When moving a n'iining machine along the mine face during the l-zert cutting operation, the slow feed is employed, and it is desirable at this time that an excessive force shall not be used for advancing the machine in order that the out ter bits may not be crowded against the work when the cutting'is difficult or the bits are dull. As above explained, the lever 69 is moved in a clockwise direction in order to produce a relatively light frictional engagement between the clutch members 26 ant 27, and. in a counter-clockwise direction produce a relatively heavy frictional engagement of said parts. In order to prevent the latter movement of the lever 69 when the handle 94 is in the slow feed position B, the lever 69 is provided with a pro-- jcction 98 adapted to engage the handle 94 when the latteris in the position B, thereby preventing counter-clockwise movement of the lever 69 while permitting clockwise movement thereof.

In Fig. 8 is illustrated a modification of the pressure generating mechanism, shown in F ig; 3. As shown in Fig. 8, the pressure cylinder 99, having a passage 100 leading to the friction devices and corresponding to the passage 41, is provided with a lining con'iprising head members 101 and 102 and a spacing member 103 having an annular groove 104 communicating with the passage 100 and l'iaving radial ports 105 communi- .ating with the interior of the cylinder. The several members of the lining are held. in assembled position in the cylinder 99 by a screw" plug 106, and have between them suitably disposedcup leathers 107. Mounted to reciprocate within the cylinder lining, is a piston .108 having a piston rod 109 pro vided with a groove to receive the forked end 73 of the controlling lever 69. The piston 108 is provided with anaxially disposed chamber 110 comrminicating through passages 111 and 112 with the cylinder at opposite sides of the piston, the inner ends of said passages being controlled by valves 1.13 and 114 between which is interposed a spring 115. The valve 114 and passage 112 are preferably smaller than the valve 113 and passage 111, so that the area of that portion of the valve 114 which is subjected to the pressure in the passage 112 is smaller than the area of that portion of the valve 113 which is subjected to the pressure in the passage 111. The chamber 110 also communicates with the lateral face of the piston 108 through radial ports or passages 116. The piston 108 is further provided with a chamber 117 connected by longitudinal passages 118 and 119 with the opposite ends of the piston and with a radial port 120 affording communication between said chamber and theports 105. l Vithin the chamber 117 is a preferably spherical valve 121 adapted to seat itself at the inner end of either of the passages 118 or 119. 7

With the parts in the position shown. if the lever 69 'bemoved in a clockwise direction, pressure will be generated in the right end of the cylinder 99, which. pressure will be transmitted through the passage 118, chamber 117 ports 120 and 105, groove 104. and passage 100 to the friction mechanism. The valve 121, being at this time seated at the inner end of the passage 119. will. pr Vent flow of liquid from the right to the left end of the cylinder. The pressure above re ferred to will also be transmitted through the passage 111 to the valve 113, and-when said pressure becomes sufficient to overcome the tension of the spring 115. said valve 113 will be unseated and liquid from the right end of the cylinder will pass through the chamber 110 and left passage 116 to the left end of said cylinder, the cup leathers 107 being so disposed as to permit the liquid to flow in this manner.

If the lever 69 be moved in a counterclockwise direction. the pressure of the fluid in the left end of the cylinder will cause valve 121 o be unseated from the inner end of the passage 119 and to seat itself at the inner end. of the passage 118. Thereafter. pressure will be built up in the left end of the cylinder and. will be transmitted through the passage 119, chamber 117, ports 120 125, and passages 10 1 and 100 tothe-friction mechanism. This pressure will also act through the passage 112upon the valve 114:. and, when sufficient to overcome the tension of the spring 110, will unseat said valve. thereby limiting the amount of pressure which may be generated. in the left end of the cylinder.

Inasmuch as the valves 113 and114t are held to their seats with the same initial. spring pressure but have different areas ex posed to the pressures in the passages 111 and 112, respectively it will be seen that a greater pressure in the left end of the cvlinder isrequired to unseat the valve 114 than is required. in the right end of the cylinder to unseat the valve 113. Consequently it will be seen that by moving the lever 69 in a counter-clockwise direction the friction devices may be loaded with a greater pres sure than by moving said lever in. a clock= wise direction. 1

11 1 without disassembling the entire pressure mechanism.

In order to avoid leakage about the piston. rod 109 and stem 123, cup leathers 125 are preferably clamped between the cylinder head member 101 and the end of the cylinder 99, and between the plug 106 and the cylin' der head member 102 respectively.

In the modified form of the invention shown in F igs. 9 and 10, pressure in the by draulic clutch operating mechanism is preferably generated by a pump, herein shown as composed of a pair of gears 200, one of which is preferably detachably secured. as by a keyway 201, to a vertical shaft 202 which is constantly driven by the gear 14:. The pump is preferably located in the cover 203 of the mining machine frame. and forces oil or other liquid from a small reservoir 204: through a passage 205 to a valve casing 206 containing a rotary controlling valve .207. From the valve casing 206, passages 208 and 209 lead to opposite ends of a cylinder 210 comprising coaxial small and large cylinder portions 211 and 212, respectively. and containing a differential piston 213 ha ing small and large piston heads 214. and 215 fitting said small and large cylinder portions, respectively. l i hen the valve 207 is turned to the position shown in Fig. 9. a passage 216 therein connects the passages 205 and 208, and the pressure generated by the pump is exerted on the oil in the outer end of the small cylinder portion 211 from which a passage 217 leads to the clutch mechanism. The pressure is transmitted. as just described when it is desired to feed the mining machine slowly. When it is desired to feed the machine more rapidly and to use a greater frictional engagement between the clutch members the controlling valve 207 is' turned to move the passage 216 out of communication with the passages 205 and 208 and cause a second passage 218 in said valve to connect the passage 205 with a passage 209 leading to the large cylinder portion 212. so that the pressure from the pump is exerted upon the large piston head 215. As will be obvious, the pressure on this large piston head creates a much higher pressure per square inch on the smaller pistonhead 21 1, and since the liquid acted on by said smaller piston head cannot escape through the valve 207, a higher pressure is generated, in the flow from the passage 205 to theme vides for an easy control of the fl w tlrr and since. there is no fluid flow through the friction mechanism and back ,to the reservoir a pressure governed bypass 222 is provided between the supply passage 205 and the return passage 220, a pressure go:-

erned valve 223, herein shown as of the spring pressed check valve type, being pro vided in this bypass to govern the pressure impressed by the pump on the lien; The va ve 223. is held seated by s p 224 whose pressure, or load upon the valve, is adjustable by means of a screw plug Means ar also provided for automatically replenishing the supply of liquid in the pas sages above described should any loss occur. through accidental leakage, said. means pref- I e-rably comprising a reservoir 1 01 eed the cover 203 and communicating; with the passage 205 through a passage baclr being prevented by a small check valve 228. This check ever, held in position by a very light spr' 229, so that when the pump is oil will flow past the check it passage 205 to replace the oil winch may have been lost through leakage.

The construction above described pre l from the pump to generate either of two pressures in the friction mechanism, these pressures being readily governed by adjustment of the valve 207 controlling the com. munication between the several passages. It will be seen that no other adjustm en of the mechanism is necessary, as the supply of oil or other liquid in the pressure system is automatically maintained constant by {the provision of the reservoir 226 and check valve 228. The cylinder 210 is preferably provided with a removable outer ead-230 having a guide 231 for a stem on the differential piston 213, the removal of said head permitting inspection of the cylinder,

withdrawal of the piston, and renewal of the packings without removing the entire cover or otherwise disassemhling the ma chine."

Asomewhat simplified form of the invention is illustrated in Fig. 11, wherein the ecylinder cover 300 is formed with .a p: 301communicating with the nism through ,a passage 302 in Within the cylinder 301 is a piston ing the usual packing leathers 304 and adapted to be forced downwardly in said cause a corresponding longitudinal. movement of the piston 303 in the cylinder 301.

For limiting the pressures which may -be transmitted from the cylinder 301 through the passage 302 to the friction mechanism, there is provided a pair of relief dewiees comprising cylinders 307 and 308, prefeu ably formed integral with the cover 300 and containing hollow pl-ungers 309 and 310, respectively, said cylinders communicating at their inner ends with the passage 302 through passages 311 and 312. The plungers 309 and 310 are normally forced inwardly by means of springs 313 and 314 within said plungers and engaging at their outer ends screw plugs 315 and 316 in threaded engagement with the outer ends of the cylinders 307 and 308, whereby said springs may be placed under an initial tension, said plugs being secured in adjusted position by means of a suitable seal 317.

One of the springs, for example, the spring 31 1-, is heavier or stronger than the other of said springs. \Vhen, therefore, the lever 303 is operated to depress the pie ton 303, the pressure generated in the cylinder 301 will be transmitted to the friction mechanism until said pressure equals or exceeds the initial tension of the spring 313, whereupon said spring will yield, permitting upward movement of the plunger 309. Further depression of the piston 303 will, therefore, not result in any considerable increase in the pressure applied to the friction mechanism until the plunger 309 engages the plug 315 and is arrested thereby. Thereafter, further downward movement of the piston-303 will cause an in creased pressure to be transmitted to the friction mechanism until said pressure equals or exceeds the initial tension of the spring 314, whereupon said spring will yield, permitting an upward movement of the plunger 310 and preventing the transmission of further pressure to the friction mechanism. The proportion of the parts is preferably such that the piston 303 cannot be moved a sufficient distance to cause the plunger 310 to engage the .plug 316, so that themaximum pressure which may be transmitted in the friction mechanism is limited by the adjustment or" the plug .316 and consequent initial tension of the spring 314.

As in the constructions previously described, the volume of liquid in the pres,

sure system is maintained against leakage loss by a reservoir 318 communicati with the passage 302 through a port 319 controlled by a check valve 320 normally hold seatedby a light spring 321 Another modification of the invention is shown in Fig. 12, wherein the cover 400 is formed with a cylinder 401, the inner end of which communicates through a passage 402 with the friction mechanism. Working in the cylinder 401 is a hollow piston 403 having theusual packing leathers 404 and normally held in the outermost position shown by means of a light spring 405. Within the piston 403 is a spring 406 engag ing atits outer end a washer 407, which is normally seated against a bushing 408 in threaded engagement with the interior of the piston at the outer end thereof, whereby, by adjusting said bushing, the spring 406 may be held under initial tension between the washer 407 and the inner end of the piston. The washer 407 also engages a nut 409 on a threaded stem 410 projecting inwardly from a hollow plunger 411 guided for movement in the outer end of the cylinder 401 and retained therein by a cap or bushing 412. lvithin the plunger 411 is a spring 413 bearing at its outer end against a flange or collar 414 on a second plunger 415 retained in the plunger 411 by means of a bushing 416 in threaded engagement -with the outer end of the plunger 411,

whereby, by adjusting said bushing, the spring 413 may be held under a predetermined initial tension between the collar 414 and the inner end of the plunger 411. The cap or bushing 412 is preferably formed with an inturned lip or flange 417 overlying the bushing 416, so that by applying a suitable seal 418 to said bushing 412 unauthorized adjustment of the bushing 416 is prevented.

The outer end of the plunger 415 engages the periphery of a cam 419 carried by a pivotedcontrolling lever 419, whereby angular movement of said lever will cause longitudinal movement of the plunger 415,

v The spring 406 is preferably stronger or under a greater initial compression than the spring 413, lVhen, therefore, the lever 419 is operated, the initial compression of" the springs 406 and 413 will cause the plungers 415 and 411 and the piston 403 to move inwardly as a unit, thereby generating in the inner end of said cylinder a pres sure which will be transmitted through the passage 402 to the friction mechanism. Vhen this pressure equals or exceeds the initial compression of the spring 413, said spring will yield, permitting further in ward movement of the plunger 415 without corresponding inward movement of the plunger 411 and piston 403, and consequently without transmitting any very substantial additional pressure to the friction mechanism. When, however, the inner end of the plunger 4.15 engages the inner end of the plunger 411, the parts will again move forward as a unit with a resultant in creased pressure upon the friction mechanism. When this increased pressure exceeds the initial tension of the spring 406,however, the latter spring will yield, permitting inward movement of the plungers 415 and 411 without corresponding movement of the piston 403, and consequently without very greatly increased additional pressure upon the friction mechanism Oil or other liquid is supplied to the cylinder 401 from a reservoir 420 communicating with said cylinder through a passage 421 controlled by a check valve 422 normally seated by a light spring 42-3.

A further modification of the invention is shown in Fig. 13, wherein the cover 500 is formed with two cylinders 501 and 502, the cylinder 502 communicating with the cylinder 501 through a passage 503 and with the friction mechanism through a passage 504. Within the cylinder 501 is a hollow plunger 505 havingsuitable packing 506 and normally forced inwardly by a spring 507 engaging at its inner end the inner end of said plunger and at its outer end a plug 508 in threaded engagement with the outer end of the cylinder 501, whereby, by adjustment of said plug, the spring 507 may be placed under a predetermined initial tension, inward movement of the plunger 505 being limited by engagement of an exterior shoulder 509 thereon with a corresponding interior shoulder 510 in the cylinder, and outward movement of said plunger being limited by a stem 511 extending inwardly from the plug 508 within the plunger 505 and adapted to engage the inner end thereof.

Within the cylinder 502 is a piston having the usual packing 513. Guided for longitudinal movement in the piston 51.2 is a sleeve 514 having an open inner end and a closed outer end between which and the closed inner end of the piston is interposed a spring 515. The sleeve 514 is formed adj acent its outer end with an exterior shoulder 516 which is engaged by a bushing 517 in threaded engagement with the outer end of the piston 512, whereby, by adjusting said bushing, the spring 515 may be held under a predetermined initial tension between the inner end or" the piston and the outer end of the sleeve.

The plug 508 and bushing 517 may be held against unauthorized adjustment to vary the initial tensions of the springs 507 and 515 by means of a suitable seal 51S connectingsaid plug and bushing. The initial tension of the spring 515 is preferably greater than that of the spring 507.

The closed outer end of thesleeve 514 engages the edge of a cam 519 carried by a pivoted controlling lever 519, whereby angular movement of said lever will cause longitudinal movement of said sleeve. By reason of the initial tension of the spring 515, inward movement of said sleeve will be accomplished by a corresponding; inward movement of the piston 512, thereby applying to the liquid in the inner end of the cylinder 502 a pressure which will be trans mitted through the passage 504: to the friction mechanism. When this pressure exceeds the initial tension of the spring 507, said spring will yield, so that further in ward movement of the piston 512 will be accompanied by a corresponding outward movement of the plunger 505without greatly increasing the pressure upon the friction mechanism. lVhen, however, the plunger 505 engages the inner end of the stem 511.. thereby arresting the outward movement of said plunger, further inward movment of the piston 512 will result in a more pro nouncedly increased pressure upon the friction mechanism. When this increased pressure equals or exceeds the initial tension of the spring 515, the latter will yield, permitting continued inward movement of the sleeve 51 1- without corresponding movement of the piston 512, and consequently without further very substantially increasing the pressure on the tension mechanism.

The cover 500 is formed, between the cylinders 501 and 502, with an oil reservoir 520 communicating with the cylinder 501 and with the interior of the piston through a port 521. The head of the piston 505 is formed with a port 522 controlled by an inwardly opening check valve 523 normally held seated by a light spring 524, whereby the supply of liquid in the pressure system may be maintained against leakage losses from the reservoir 520.

YVhile I have in this application specifically described several embodiments which my invention may assume in practice, it will be understood that these forms are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In combination an actuator, a driving member, power transmission connections etween said actuator and driving member including cooperating friction clutch members and means for manually imparting any one of a plurality of automatically limited hydraulicpressures to said clutch members to effect engagement thereof for rotation at equal angular speeds including a manually moi able'member upon which force is xerted to effect engagement of said clutch mem bers and yielding means associated with said manually movable member and through which the force applied acts to effect application of said hydraulic pressures to said clutch members.

2. In combination, an actuator, a driving member, power transmitting connections between said actuator and driving member including cooperating friction clutch members, and controlling means for applying hydraulic pressure to said clutch members to engage them for rotation at equal angular rates including a plurality of yielding means respectively yielding when subjected to different pressures operative to effect application of different definite pressures to said clutch members to effect engagement thereof.

3. In combination, an actuator, a driving member, power transmitting connections between said actuator and driving member and including cooperating friction clutch members, and controlling means for applying hydraulic pressure to said clutch members to engage the same, said controlling means having a plurality of yielding elements adapted respectively to limit said hydraulic pressure to different predetermined amounts.

1. A mining machine comprising fast and slow feed mechanism, a friction clutch controlling each of the same, and hydraulic control mechanism for said friction clutch having provision for automatically maintaining different loading limits for said fast and slow feeds.

5. A mining machine having feeding mechanism comprising, in combination, an actuator, a feeding member, power transmit-- ting connections between said actuator and feeding member and including cooperating friction clutch members, and means includ ing a friction controlling member for gencrating and applying an automatically lim ited hydraulic pressure to said clutch mem bers to engage the same.

6. A mining machine having feeding mechanism comprising, in combination, an

actuator, a feeding member, power transmitting connections between said actuator and feeding member and including cooperating friction clutch members, and controlling means including a friction controlling memher for generating and applying hydraulic pressure to said clutch members to engage the same, said controlling means having a yielding element for limiting the amount of said hydraulic pressure.

7. A mining machine having feeding mechanism comprising, in combination, an actuator, a feeding member, power transmitting connections between said actuator and feeding member and including coopcrating friction clutch members, hydraulically operated means for engaging said clutch members, and pressure generating means including a friction controlling member for generating and applying hydraulic pressure to said hydraulically operated means, said pressure generating means having a yielding element for limiting the amount of said hydraulic pressure.

8. A mining machine having feeding mechanism comprising, in combination, an actuator, a feeding member, power trans mitting connections between said actuator and feeding member and including cooperating friction clutch members, and means including a friction controlling member for generating and applying any one of a plurality of automatically limited hydraulic pressures to said clutch members to engage the same.

9. A mining machine having feeding mechanism comprising, in combination, an

actuator, a feeding member, power transmitting connections between said actuator and feeding member and including cooperating friction clutch members, and controlling means for applying hydraulically pressure to said clutch members to engage the same, said controlling means having a plurality of yielding elements adapted respectively to limit said hydraulic pressure to different predetermined amounts.

1O. A mining machine having feeding mechanism comprising, in combination, an actuator, a feeding member, power'transmitting connections betvven said actuator and feeding ,member and including cooperating friction clutch members, hydraulically op erated means for engaging said clutch members, and pressure generating means for ap plying hydraulic pressure to said hydraulically operated means, said pressure generating means having a plurality of yielding elements adapted respectively to limit said hydraulic pressure to different predetermined amounts. 1

11. A mining machine having feeding mechanism comprising, in combination, an actuator, a feeding member, power transmitting connections between said actuator and feeding member and including cooperating friction clutch members, hydraulically operated means for engaging said clutch members, pressure generating means including a friction controlling member for generating and applying hydraulic pressure to said hydraulically operated means, and means for actuating said pressure generating means, said actuating means having a yielding element for limiting the amount of said hydraulic pressure. I 7

12. A mining machine having feeding mechanism comprising, in combination, an actuator, a feeding member, power transmitting connections between said actuator and feeding member and including coo perating friction clutch members, hydraulically operated means for engaging said clutch members, a cylinder and piston for applying hydraulic pressure to said hydraulically operated means. and actuating means for said piston including a member rigidly connected thereto, said actuatingmeans including a mechanism comprising, in combination, an

actuator, a feeding member driven thereby, friction clutch members between said elements, hydraulically operated means for engaging said members, and pressure generatingmeans for applying any one of a plurality of predetermined pressures to a liquid in said hydraulically operated means, a reservoir, and conections between said reservoir and said hydraulically operated means for automatically maintaining a'substantially constant quantity of liquid in said hydraulically operatedmeans and said pressure gen erating means.

15. A; mining machine having feeding mechanism comprising, in combination, an actuator. a feeding member driven thereby, cooperating friction clutch members between said elements, hydraulically operated means for engaging said members, pressure generating means for applying any one of a plurality of predetermined maximum pressures to a liquid in said hydraulically oper ated means, means for adjusting the limits of said pressures, a reservoir, and connections between said reservoir and said hydraulically operated means for automatically maintaining a substantially constant quantity of liquid in said hydraulically operated means and said pressure generating means.

16. mining machine having a machine frame and feeding mechanism comprising an actuator, a feeding member driven there by, cooperating friction clutch members between said actuator and said shaft, hydrauli cally operated means for engaging said members, pressure generating means for applying any one of a plurality of predetermined pressures to a liquid in said hydraulically operated means, a liquid reservoir formed integral With said machine frame, and connections between said reservoir and said hydraulically operated means for automatically maintaining a substantially constant quantity of liquid in said hydraulically operated means and. said pressure generating means.

17. A mining machine having feeding mechanism con'iprising, in combination, an actuator, a feeding member driven thereby, cooperating friction clutch members between said actuator and said feeding member, hydraulically operated means for varying the frictional engagement of said clutch members, and a plurality of adjustable limiting means for varying the pressure limit to be applied to the hydraulically operated means.

'18. A mining machine having feeding mechanism comprising, in combination, an actuator, a feeding member driven thereby, clutch mechanism controlling the operation of said shaft by said actuator, hydraulically operated controlling means for said clutch mechanism, and pressure generating means including a friction controlling member movable in opposite directions to apply prcssure to. a liquid in said hydraulically operated means. v

19. A mining machine having feeding mechanism comprising, "in combination, an actuator, a feeding member driven thereby, clutch mechanism controlling the operation of said feeding member by said actuator, hydraulically operated controlling means for said clutch mechanism, and pressure generating means movable in opposite directions to apply pressure to. a liquid in said hydraulicall operated means, said last named means being movable in one direction to, apply a greater pressure than when moved in the other direction.

20. A mining machine having feeding mechanism comprising, in combination, an actuator, a feeding member driven thereby, clutch mechanism controlling the operation of said feeding member by said actuator, hydraulically operated controlling means for said clutch mechanism, pressure generating means movable in opposite directionsto apply either of two maximum pressures to a liquid in said hydraulically operated means, and means for varying the maximum pressures.

21 A mining machine having feeding mechanism comprising, .in combination, an actuator, a feeding member driven thereby, clutch mechanism controlling the operation of said feeding member by said :mtuator, hydraulically operated controlling means for said clutch mechanism, manually op erable pressure generating means movable in one direction to apply to the liquid in said hydraulically operated means any pressure desired under a certain limit and movable in the opposite direction to apply to said liquid any pressure desired under a certain limit, and means for varying both of said limlts.

2-2. A niiimng machine having feeding mechanism comprising, in combination, an

actuator, a feeding member driven thereby,

clutch mechanism controlling the operation lever in one direction.

23. A mining machine having feeding mechanism comprising, in combination, an actuator, a feeding member, connections between said actuator and feeding member including a variable transmission mBCllftHlSll'l and a pair of cooperating friction clutch members, a lever for controlling said transmission mechanism, hydrauli'ca'lly operated means for controlling the engagement of said clutchmembers, and pressure generatin means for applying any one of a plura 'ty of predetermined pressures to a liquid in said hydraulically operated means, said pressure generating means and controlling lever having interengaging means for limiting the operation of said pressure generating means when said lever is in one position.

24. A mining machine comprising a frame, a cover therefor, feeding mechanism comprising an actuator, a feeding member driven thereby, and cooperating friction clutch members interposed between said actuator and feeding member, said actuator, feeding member, and clutch members being mounted on said frame, and hydraulically operated means carried by said cover for controlling the engagement of said clutch members and comprising pressure generating means for applying any one of a' plurality'of predetermined pressures to a liquid in said hydraulically operating means and a conduit communicating with said pressure generating means and said hydraulically operated means.

25. A mining machine comprising a frame, a cover therefor, feeding mechanism comprising an actuator, a feeding member driven thereby, and cooperating friction clutch members interposed between said actuator and feeding member, said actuator, feeding member, and clutch members being mounted on said frame, hydraulically operated means for controlling the engagement of said clutch members, pressure gen crating means carried by said cover and detachably connected With said hydraulically operated means, said pressure generating means comprising. means for applying any one of a plurality of predetermined pres- Jill sures to a liquid in said hydraulically operated means, and liquid conducting means for connecting said pressure generating means and said hydraulically operated means, said conducting means being detachably secured to the latter.

26. A mining machine comprising a frame, a removable cover therefor, feeding mechanism comprising an actuator, a feeding member driven thereby, and cooperating friction clutch members interposed between said actuator and feeding member, said actuator, feeding member, and clutch members being mounted on said frame, hydraulically operated means carried by said cover for controlling the engagement of said clutch members and comprising pressure generating means for applying any one of a plurality of predetermined pressures to a liquid in said hydraulically operated means and a conduit connected to said pressure generating means and said hydraulically operated means, and means in said conduit for closing communication between said hydraulically operated means and said pressure generating means.

2?. In a mining machine, feeding mechanism, a friction clutch controlling the same, and hydraulic controlling means for said friction clutch including a cylinder, a piston rod, oppositely disposed spring pressed pistons movable thereon, an operating member, and oppositely acting resilient means operatively connected between said rod and said operating member.

28. in combination, a friction clutch, pressure fluid operated means for connecting the elements thereof, a conduit leading to said means, pressure generating means communicating with said conduit, a reservoir communicating with said conduit, and a valve for said conduit opened by fluid in said reservoir and closed by pressure generated by" said generating means.

29. In combination, a friction clutch, pressure fluid operated means for connecting the elements thereof, a conduit leading to said means, pressure generating means communicating with said conduit, a reservoir communicating with said conduit, a valve for said conduit opened by fluid in said reservoir and closed by pressure gencruted by said generating means, and an other valve between said valve and said clutch.

30. in combination, clutch mechanism in cluding a plurality of clutch elements, hydraulic operating means for connecting said elements, a conduit leading therefrom, a cylinder comn'mnicat'ing with said conduit, a piston rod extending into said cylinder, a pressure piston in said cylinder, an operating member, and a resilient connection betw en said operating member and said rod to substantially limit the pressure in said cylinder.

31. In combination, clutch mechanism including a plurality of clutch elements, nydraulic operating means for connecting said elements, a conduit leading therefrom, a

cylinder communicating with said conduit, a piston rod extending into said cylinder, oppositely disposed pistons movable thereon in said cylinder, resilient means forcing said pistons apart on said rod, an operating member, and a plurality of resilient connections of different strengths connected between said operating member and said rod.

32. In combination, clutch mechanism including a plurality of clutch elements, hydraulic operating means for connecting said elements, a conduit leading therefrom, a pressure generating cylinder communicating with said conduit, a piston rod extending into said cylinder, oppositely disposed pistons movable thereon in said cylinder, resilient means forcing said pistons apart on said rod, an operating member, a plurality of resilient conenctions of different strengths connected between said operating member and said rod, and means for adjusting the strength of said resilient connections.

33. In combination, clutch mechanism including a plurality of clutch elements, a hydraulic operating means for connecting said elements, a conduit leading thereto, a cylinder member, a removable lining therein having communications with said conduit, a piston rod extending into said lining, oppositely acting pistons movable on said rod within said lining, resilient means forcing said pistons apart on said rod, a plurality of coiled springs of different strength carried on said rod, an operating member having a portion extending between and acting upon the adjacent ends of said springs, and means for adjustably connecting the opposite ends of said springs to said rod.

34. A. mining machine including an actuator, a. feed driving member, plural train power transmitting connections between said actuator and feed driving member, hy draulic controlling mechanism for said trains including a hydraulically operated friction clutch, and means for automatically maintaining different definite loading limits for said different trains.

35. A mining machine including an actuator, a. feed driving member, plural train power transmitting connections between said. actuator and said feed driving member, controllingmechanism including hydraulically operated frictional controlling means for said trains, and means for automatically maintaining different definite loading limits for said frictional controlling means durin the operation of said different trains.

36. A mining machine including an actuator, a feed driving member, power transmitting connections between said actuator and member including means for elfecting reverse rotation of the latter and hydraulic controlling mechanism for providing automatically limited different loading limits for different directions of drive. i

37. In a mining apparatus, a mining machine having feeding mechanism including 10 flexible feeding means having a plurality of flexible feeding portions having free extremities adapted for connection to fixed points, and means for Winding in either of said oortions at a plurality of materially dili'crent speeds including hydraulically oporated frictional controlling means having different predetermined loading limits for said diflierent speeds.

In testimony whereof I affix my signature.

MORRIS P. HOLMES. 

